Handheld units are becoming an increasingly popular way of packaging portable electronic devices. Examples are cellular telephones, small tape recorders and bar code readers. With the advent of microelectronics, increasing computational power and more convenience features are being put in portable electronic devices. The increased computational power and greater number of convenience features generally results in an increased number of control functions in such electronic devices, and usually such control functions are realized by means of an array of buttons in a keypad, a visual readout of a display unit, and a confirming sound maker.
There is an obvious trade-off between the decreasing size of the portable electronic unit and the number of control functions it can perform. One place where this trade-off is most visible is in the amount of surface area that the portable electronic device presents to its user. Keypads with a given number of keys cannot be made smaller than a certain size without inconveniencing users with even average size fingers. The size of display units cannot be decreased beyond a certain point or they become unreadable by the user. Further, the size of a sound maker cannot be decreased beyond a certain point, or the fidelity and audibility is too badly degraded for user acceptance. Therefore, it is common for the entire front surface area of a portable electronic device to be used entirely to hold a keyboard, a display unit and a miniturized speaker, in order to avoid reducing the size of any one of these items below the size that would be acceptable by users. It would be advantageous to remove at least one of these items from the front side of device (without degrading its performance or the acceptability of the device to users).
Many of the portable electronic devices that are currently in use must be capable of operating in areas that have high sound levels. For example, bar code readers are commonly used in noisy production areas where it is hard for the user to hear any confirmatory sound signals generated by the device. Further, several such devices are also commonly used within a small work area, increasing the chance that the confirmatory signal from one such device will be misinterpreted as being a confirmatory signal from another such device. Therefore, it is desirable to have a portable electronic device that can produce highly intense sound signals that are primarily presented to the user (without requiring that the sound maker be positioned at the front side of the device).